- (void)scrollViewDidScroll:(UIScrollView*)scrollView{
    if ( scrollView == self.conversationListTableView ){
        CGFloat sectionHeaderHeight = 46;//这个高度就是你的header的高度
        if (scrollView.contentOffset.y <= sectionHeaderHeight&&scrollView.contentOffset.y >= 0){
            scrollView.contentInset= UIEdgeInsetsMake(-scrollView.contentOffset.y,0,0,0);
        } else if (scrollView.contentOffset.y >= sectionHeaderHeight){
            scrollView.contentInset= UIEdgeInsetsMake(-sectionHeaderHeight,0,0,0);
        }
    }
}